One of the earliest devices to measure time were the sundials which used suns motion across the sky as a standard of measurement for time. The use of units like seconds and minutes which are radial angle measurements in geometry points toward the original connection of time measurements to radial motion of astronomical objects across the sky. Once we started using accurate time keeping watches, clocks and digital devices capable of measuring time independent of the celestial connection time developed a life of its own.

When we measure the speed of a car, we are just comparing its motion to the motion of the hands of the clock and also indirectly to the fractional motion of sun across the sky. We seem to be measuring speed with something abstract called time; we are actually just comparing a known motion (of the sun) with an unknown motion of the car. Time is a way to compare or describe different kinds of motions like speed of light, how fast heart beats or how frequently earth spins around its axis. But these processes could be compared directly without making reference to time. Time may have no independent existence it may be just a common unit of motion making the world that is filled with motion easier to describe. TIME CHANGE MOTION AND FORCES

Time is a real phenomenon a continuous change through which we live. Time becomes evident through motion; sunrise sunsets, night and day, the changing seasons, the movement of the celestial bodies all is indicative of continuous change. The aging process is a reminder that molecular motion and interactions are also at work and are a part of time. Other important aspect of time is presence of motion of particles like photon and the motion at the atomic level. An often overlooked but very important aspect of time is that forces also act in time.

More powerful than all the armies of the world, is an idea whose time has come.........Victor Hugo

We perceive time as past present and future. The most real perception of time appears to be in the moment we call present, however almost all of what we perceive as the present is already past. The present is a fleeting moment; whatever is happening now (present) is confined to an infinitesimally narrow point on the time line which is being encroached upon by what we think of as the past and the future. Present resembles the sharp point of a recording laser or needle; it may be the mental awareness of recording of memory as it is being inscribed into our brain. A person who goes to an event but falls asleep would have no recollection of it as if the event did not exist in his past. Unless we are consciously aware of an event it does not seem to enter our past memory.

Unlike the present the past and future are measurable durations of time. Past historical events, a meeting, or a wedding reception, are all measurable durations or extensions in time, just like a recorded material on tape. This similarity suggests that past is just a recorded memory, while future can be compared to an unrecorded tape.

Historical events have in them the same time characteristic as stories that are just creations of human imagination. Both contain in them the time concepts of earlier, the later, the past the present and the future; this again suggests that past really is similar to memory of events.

Future appears to be a projection created by our past experiences stored in our memory. The fact that the present which gives us the most real feel of time cannot be measured while the inaccessible past and future can be measured as durations strongly suggests that the way we perceive time (present-ism or the block universe view) is an illusion.

SUMMARY

1. We measure time by comparing one standard motion against another. Time may not have any independent existence. Time and clocks are used for convenience. The motion could have been compared directly.

2. Motion alone is not enough to explain time. Forces also appear to be part of time. Arrow of time may be explained if we think of time as presence of forces and motion.

3. Perception of time as past present and future gives us the illusion of the passage of time as well as the block universe view of time. Above it is shown that this perception may just be an illusion and time is more like memory and recording devices. The similarity of time characteristic of past present and future in historical events and made up stories also suggests that our perception of time is an illusion and this aspect of time is also like a record. The fact that the present which gives us the most real feel of time cannot be measured while the inaccessible past and future can be measured as durations strongly suggests that the way we perceive time (present-ism or the block universe view) is an illusion.

4. Slowing of time in motion and gravity does not lead to disappearance into the past as should happen if there was block universe. Absence of time travellers from futuristic advanced civilizations is also against the concept of the block universe.

5. The concept of origin of the universe in the Big Bang is at complete odds with the block universe view of time. If the block universe which is supposed to be laid out as a time-scape (from the past to the present to the infinite future) exists and began in big bang then it would mean that all of the time up to the infinite future would come into existence in the instant of the big bang. This idea is truly preposterous.

6. Slowing of time in gravity and in motion as well as the ultimate speed limit c provides us the necessary clues to understanding the cause of the phenomenon of time however we need to first convince ourselves that time is a process that is linked to motion and forces and the block universe view of time is not correct.

WHAT IS TIME AND WHAT CAUSES TIME?

TIME AS A BLOCK UNIVERSE

"People like us who believe in physics know that the distinction between the past, the present and the future is only a stubbornly persistent illusion" Albert Einstein

Every event in time has a place like feeling to it, giving support to the block universe view of time in which time is fixed and laid out like a time-scape. In the block universe past, present and future exist together superimposed in different dimensions. This view of time suggests that dinosaurs are still alive and roaming the earth in other time dimensions; so are multiple copies of us and the whole universe. This view is reinforced by Einstein’s General Relativity (GR) in which time extends as the fourth dimension from the past to the future. Lack of simultaneity in Einstein's SR and an interpretation of the Lorentz transformation equation known as the Rietdijk–Putnam argument also promote this view to explain the Andromeda paradox as an alternative reality existing in a different time dimension.

Time in the block universe is laid out as time-scape similar to landscape; future and past already exists and there cannot be a free will. Even in the smallest duration of time in a block universe there should be infinite number of copies of everything including the whole universe. Block universe leads to a few problems and paradoxes. How do we explain the origin of universe as all parts of the block universe exist all the time? If there is a big bang in block universe then even now it exists. If time-scape is already laid out then what causes us to move through this time-scape? How does our consciousness move across time? What makes it move and why we cannot willfully move it anywhere anytime?

If concept of block universe is correct then there should exist in time future civilizations millions or billions of years more technologically advanced then us. At least some of them should be capable of time travel. We should have seen some evidence for that, unless there is some law of the universe which prohibits time travel. Then there is the possibility of time travel paradoxes including the grandfather paradox in which a person travels to the past and kills his grandfather thereby changing the future so that the time traveler would not exist and thus not travel to the past to kill his grandfather.

BIG BANG IN THE BLOCK UNIVERSE?

Imagine two objects one moving in orbit around the other in space. Now suppose from our distant observation point of a fixed time we observe time to get slower in the area where these two objects are moving. We expect to see slower motion? We also should observe proportionally weaker (gravitational) force; otherwise the objects will get pulled together. If we observed faster time, we expect to see faster motion and stronger forces to keep the objects from flying apart. While with zero time motion will freeze and force will become zero. The increase or decrease in strength of forces is only in relation to our fixed time from where we are making the observation. From the point of view (time) of the orbiting objects neither motion nor force has changed. As this thought experiment also can be extended to particles held together by electromagnetic forces we can say that time involves both motion and forces.

PERCEPTION OF TIME: THE PAST THE PRESENT AND THE FUTURE

“Life is enslaved to the passage of time Except for this moment which is free”

Theory of Relativity predicts slowing of time with motion and gravity. These predictions are confirmed in particle accelerators and gravity experiments. Twin paradox discussions may have served as a distraction from obvious question that arises; if there is a block universe why particles and masses with slower time do not disappear into the past? In gravitational fields space is clearly continuous between areas of slower and faster time. Black holes with their intense gravity that bring time to a screeching halt do not disappear from our present into the past. Slowing of time without sliding into the past or the future suggests that time is a process and not a dimension. This may be a significant point against the block universe view of time when taken together with other aspects of time described on this page. Block universe derives its support from Lorentz transformation equations which have never been proven experimentally.

MOTION FORCES AND THE ARROW OF TIME

Most cosmologists believe that the universe originated in an event called the Big Bang about 13 billion years ago. We live in an expanding universe and the galaxies are receding from each other as a part of the universal expansion. Microwave back ground radiation which is a relic from the Big Bang has been extensively studied by many NASA and European satellites. There is no doubt in the minds of physicists and astronomers that Big Bang occurred. Similarly the concept of time being a block universe is considered a holy grail by many physicists who swear to this interpretation of Lorentz transformation. There is no discussion however on how the two diametrically opposed concepts the block universe and the origin of the universe in the big bang can be reconciled. If the universe began in the moment of the big bang and is laid out as a time-scape from the past to the present and the infinite future as required by the block universe view of time then all of the time-scape from big bang to infinite future should have begun at the moment of the birth of the universe in the Big Bang. The whole concept when taken together is ludicrous and there is no escape form this unless we discard the block universe view of time. It can be shown that this aspect of Special Relativity which depends on an interpretation of Lorentz transformation equation can be easily be given up without affecting the experimentally verified aspects of relativity.

SLOWING OF TIME IN THE BLOCK UNIVERSE

Arrow requires two points in time that can exist only in the block universe. Arrow assumes that the two points’ between past present or future exist, it also assumes that time only involves motion. Presence of forces as a part of time changes this equation as it provides the necessary gradient for the direction in time. There is also a statistical touch to this argument; smashing a glass with a hammer means application of force at one point while to assemble it back in reverse would require coordinated application of multiple tiny forces in a reverse and continuous manner which is statistically unlikely. Similarly throwing a stone into a pond creates ripples which then travel to the edge of the pond. To reverse this would require simultaneous application of multiple tiny forces at the edge of the pond to produce multiple synchronized waves moving backward to the area of splash where the stone pushed up by the ground at the bottom of the pond will be waiting to be thrown out into the hand of the thrower; a statistical impossibility.

Time presents to us in numerous ways which possibly creates difficulty in understanding this phenomenon. We are immersed in time yet we do not fully understand it. We know that time is closely linked to motion as well as forces. Theory of relativity introduced the concept of slowing of time with motion and gravity. This breakthrough could have led to further progress in understanding of time and possibly the cause of time however almost 100 years have passed without substantial progress.

There are many approaches toward understanding the phenomenon of time. We perceive time as past present and future. In physics time plays a major role in measurement of motion and forces. Einstein’s relativity introduced the concept of slowing of time in motion and gravity which have been precisely confirmed.